This invention relates generally to surveillance systems and, in particular, to a method and apparatus for improving video performance in a wireless video surveillance system.
IEEE 802.11 is a set of standards for wireless local area network communication. In particular, IEEE 802.11e pertains to wireless local area network applications through modifications to the media access control layer. This IEEE802.11e standard covers the delay sensitive applications such as streaming multimedia. Today's video surveillance systems utilize video streaming and have started using cameras with video encoders to convert the video images into MPEG video streams, for example, MPEG-4, and employing wireless technology to enhance the possible applications. In an outdoor deployment of video encoders using IEEE 802.11 protocol, typically multiple wireless video encoders connect to the network through a wireless access point in a point-to-multipoint topology. Alternatively, the system could consist of a point-to-point topology with a wireless bridge transmitting video stream from an encoder to a peer wireless bridge.
In a point-to-multipoint topology for video streaming applications, it is important to provide guaranteed bandwidth to wireless video encoders otherwise the video at the decoding station, such as a user's workstation, might look pixilated. The IEEE 802.11e standard specifies mechanisms, which enable one to provide guaranteed bandwidth. These mechanisms take into account the characteristics of traffic to allocate bandwidth. However, such implementations do not take into account the variable nature of the typical wireless channel, which can result in decreased wireless channel resources. The integrity and quality of the video images captured by a video surveillance system are critical in many security applications. Moreover, the industry demands the highest quality video even under adverse circumstances. Hence, there is a need in the industry for a method to adjust bandwidth allocation and improve video performance of wireless applications in video surveillance systems.